Low drop out (LDO) regulators are circuits that are configurable to operate with a very small input-output differential voltage, while providing a nominal regulated output voltage. Conventionally, parameters associated with such LDO regulators are adjustable based on one-time programmable methods, such as laser trimming or electrical metal wire fuse melting during production testing. Such devices are sometimes referred to as one-time-programmable (OTP) devices.
Currently, the selection of a parameter value out of a range of fixed values is implemented by metal mask options. Some LDO products offer customers the ability to select a slightly modified value relative to the nominal output voltage DC level by connecting an external control pin to ground or to a certain input voltage level. However, such devices offer limited trimming options, which may be inadequate to adjust performance of such LDO regulators under application-specific operating conditions.
High precision LDO voltage regulators require fine tuning of the DC and AC parameters, which fine tuning is typically performed during the wafer level front-end testing of the manufacturing flow. However, the assembly process produces mechanical stresses, which may induce offsets that affect the post-assembly precision of the packaged part. Conventional trimming options may be inadequate to compensate for such post assembly offsets.
In the following description, the use of the same reference numerals in different drawings indicates similar or identical items.